I think we should go a step further, as 18 U.S. Code § 31 - Definitions a (6) "The term “motor vehicle” means every description of carriage or other contrivance propelled or drawn by mechanical power and used for commercial purposes on the highways in the transportation of passengers, passengers and property, or property or cargo." By definition if you are not conducting business in the motor vehicle or use it for commercial purposes the stop shouldn't matter if you are not conducting business. I am not conducting business, thank you, have a nice day. Not a legal adviser.